US Patent 10053990 Internal rib with defined concave surface curvature for airfoil

An internal rib for a blade airfoil has a concave surface defined to ensure durability and provide desired heat transfer. A concave surface faces a pressure side or suction side outer wall. A width is between a first end and a second end, and a depth is a length of a normal depth line between a midpoint of the concave surface and an intersection point of the depth line with the pressure or suction side outer wall. An irregular arc is defined within an arc angle centered at the intersection point, the irregular arc has a first arc radius equivalent to the depth at the midpoint of the concave surface and a second arc radius where the arc angle intersects the concave surface equivalent to a product of the depth and a shape factor. The shape factor has a substantially linear relationship with the aspect ratio.